Research directions for service-oriented multiagent systems

Today's service-oriented systems realize many ideas from the research conducted a decade or so ago in multiagent systems. Because these two fields are so deeply connected, further advances in multiagent systems could feed into tomorrow's successful service-oriented computing approaches. This article describes a 15-year roadmap for service-oriented multiagent system research.     

Multibolus stimulated echo imaging of coronary artery flow

One limitation of traditional bolus tagging techniques for MR angiography is the small amount of blood labeled by one tagging, resulting in a limited filling of the downstream vessels. We describe a multiple bolus technique using stimulated echoes (STE) for imaging coronary flow. A series of radiofrequency (RF) pairs are given with each pair selective at the region of tagging, thus tagging consecutive volumes of blood, and a final nonselective pulse is given to "read out" all of the tagged spins. In this way, multiple boluses of tagged blood are imaged at one time.     

Surface generation and boundary lubrication in bulk forming of aluminium alloy

The electrical contact resistance is measured between the tool and workpiece during plane strain compression of aluminium strip coated with a non-conductive oxide film produced by anodising. Results are correlated with the observed oxide topography after the test. The purpose is to investigate the mechanism of the development of close metal-to-metal contact, the associated material transfer and their effects on the friction coefficient under boundary lubrication conditions. Initially the anodised layer provides electrical insulation between the tool and the strip but, as deformation proceeds, this layer breaks up and fresh metal is extruded through the cracks formed, causing a sharp fall in electrical resistance. Details of this behaviour are explored, showing a dependence not only on strip reduction, but also on the base oil used and the presence of boundary additives. The change in the behaviour is tracked as a transfer layer builds up on the tool.     

A Model for Mechanical Seals with Regular Microsurface Structure

A mathematical model is developed to allow performance prediction of all-liquid noncontacting mechanical seals with regular microsurface structure in the form of hemispherical pores. Seal performance such as the equilibrium face separation, friction torque and leakage across the seal are calculated and presented for a range of sealed pressure, pore size and pore ratio of ring surface area. An optimum pore size is found that depends on the other variables and corresponds to maximum axial stiffness and minimum friction torque. Also, a critical pore size is found above which seal failure is possible.     

The remarkable passivity of austenitic stainless steel in sulphuric acid solution and the effect of repetitive temperature cycling

The passivation of 316L austenitic stainless steel in sulphuric acid solution has been measured at a single temperature, and then further, after a series of temperature sweeps. After 15 h at 20 °C and constant electrode potential, the passive current density has fallen to 16 nA cm⁻² and still continues to decline, with no evidence of an approach to the steady state. After subjecting the metal to a series of temperature sweeps the passive current density has decayed much further to ca. 0.5 nA cm⁻² and probably still decaying slowly. The metal is thereby rendered extremely passive. It is argued that the passive current density as measured by conventional potential sweep voltammetry is not in fact the steady state current density, because the true approach to a steady state is far too slow.     

Kinetik der Milchkatalase beim Erhitzen

Ohne Zusammenfassungbedeutet mit Abbildungen.Mitteilung aus dem Hygienischen Laboratorium des Odessaer Medizinischen Instituts.     

Degradation of the Pt/C air cathode in acidic solution examined by cyclic thermammetry

The oxygen reduction reaction on carbon-supported platinum electrocatalysts (Pt/C) has been investigated as a function of temperature by employing the technique of cyclic thermammetry. A novel electrochemical cell has been designed which allows the concomitant measurement of the potentiostatic current from the oxygen reduction reaction (ORR) and accurate control of the aqueous electrolyte temperature, allowing cyclic linear temperature sweeps between 25 and 80 °C at speeds up to 40 mK s⁻¹. Our method provides new insight into the temperature dependent degradation of the cathodic oxygen reduction reaction in aqueous sulfuric acid systems. Cycling the temperature accelerates the degradation of the cathodic current through loss of active surface area. Two simultaneously operating mechanisms are proposed to account for this loss. One mechanism is described by physical detachment of the platinum and carbon particles under thermal fatigue, and the other by anodic dissolution of the Pt electrocatalyst. The forms of these are discussed.     

Understanding the Role of Alumina (Al2O3), Pentalithium Aluminate (Li5AlO4), and Pentasodium Aluminate (Na5AlO4) Coatings on the Li and Mn-Rich NCM Cathode Material 0.33Li2MnO3·0.67Li(Ni0.4Co0.2Mn0.4)O2 for Enhanced Electrochemical Performance

The active role of alumina, pentalithium aluminate (Li₅AlO₄, Li-aluminate), and pentasodium aluminate (Na₅AlO₄, Na-aluminate) as the surface protection coatings produced via atomic layer deposition on Li and Mn-rich NCM cathode materials 0.33Li₂MnO₃·0.67LiNi_0.4Co_0.2Mn_0.4O₂ is discussed. A notable improvement in the electrochemical behavior of the coated cathodes has been found while tested in Li-coin cells at 30 °C. Though all the coated cathodes demonstrate enhanced electrochemical cycling and rate performances, Na-aluminate coated cathodes exhibit exemplary behavior. Prolonged cycling and rate capability testing demonstrate that after more than 400 cycles at 1 C rate, the uncoated cathode delivers only 63 mAh g⁻¹, while those with alumina, Li-aluminate, and Na-aluminate coatings exhibit approximately two times higher specific capacities. The coated cathodes display steady average discharge potential and lower evolution of the voltage hysteresis during prolonged cycling compared to the uncoated cathode. Importantly, Na-aluminate coated cathode shows a lowering in gases (O₂, CO₂, H₂, etc.) evolution. Post-cycling analysis of the electrodes demonstrates higher morphological integrity of the coated cathode materials and lower transition metals dissolution from them. The coatings mitigate undesirable side reactions between the electrodes and the electrolyte solution in the cells.     

TIME-RESOLVED IMPEDANCE RESPONSE OF GUILLOTINED ALUMINIUM UNDER GALVANOSTATIC POLARISATION

1.IntroductionConventiona1frequencyresponseanalysis(FRAorEIS),althoughinprinciplecapableofresolvingallthetimeconstantsassociatedwithanelectrochemicalorcorrosionprocess,themethod,classifiedaJsasteady-statetechnique,isunabletofollowchangesinthosetimeconstantswithinshortperiodoftime.Formanycorrosionphenomenon,itisstilloffun-damentalinteresttostudyprocessesinvolvingtime-dependentparameters.Repassivationofametalsurfaceaftermechanicallystrippingitsoxidefilmisoneofsuchprocesses[1t2l.Apartfromitsin…